Research On Anode Catalysts Supported On Graphene For Direct Methanol Fuel Cell

Direct methanol fuel cell (DMFC) possesses the wide application prospect as the power source in the portable electronic products and electric vehicle etc, due to easy transportation, ease storage of the fuel, small volume, the high energy efficiency, and low pollution. However, the poor kinetics of methanol oxidation in the anodic reaction and the poisoning of the cathode resulted from methanol crossover are the two serious problems hindering the commercialization of DMFC. In this dissertation, a new anodic catalyst of the DMFC used graphene as the support was prepared. And the effects of the several preparation variables on the alloying extent, the average size, the relative crystallinity, the distribution of the metal particles, the electrocatalytic activity and stability of the anodic catalysts were investigated through the characteration of XRD, SEM, TEM and the measurements of cyclic voltammetry. The main results obtained are as follows:1. Pt/graphene catalyst was prepared using sodium borohydride as reducing agent. The Pt/ graphene catalyst was characterized by XRD and TEM techniques. The results showed the Pt nanoparticles were dispersed on surface of graphene. The average size of the Pt particles was about 3 nm. Electrochemical tests showed that the prepared Pt/graphene catalyst exhibited better performance for methanol oxidization than prepared Pt/XC-72 catalyst.2. The FGS surpported highly dispersed Pt elctrocatalyst was prepared by microwave method. The effects of the pH of precursor solution and the load proportion of Pt on electrocatalytic activity of methanol oxidation were investigated. The results showed that the Pt/FGS catalysts with 30%Pt and prepared from the pH of 8.0 all exhibited good performance for methanol oxidization.3. In ethylene glycol solution, we synthesized PtRu/FGS catalysts with different proportion of Pt-Ru atoms. The results indicated that the prepared PtRu/FGS catalyst with Pt: Ru molar ratio of about 1:1 had well size distribution of alloy nanoparticles. The three PtRu/FGS catalysts had high elecrtocatalytic activity of methanol oxidation, and they could effctively restrain CO. The catalyst with Pt-Ru proportion about 1:1 had better electrocatalytic activiy than other samples.4. The Pt/FGS catalyst was prepared by the liquid reduction method using formaldehyde as the reducing agent. The results of XRD and TEM showed the mean particle size of Pt nanoparticles in Pt/FGS was 3.2 nm, which was smaller than the commercial Pt/XC-72 catalyst from E-TEK Corp. and the Pt/FGS-M catalyst prepared using methanol as the reducing agent. The electroactivity of the catalysts for methanol oxidation was studied. The results showed that the Pt/FGS catalyst possessed the better electrocatalytic activity for methanol oxidation than that of Pt/XC-72 and Pt/FGS-M catalysts. Therefore, the reduction rate had an important influence on the prepared catalysts.